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4	<head>	4	<head>
5	<title>libev</title>	5	<title>libev</title>
6	<meta name="description" content="Pod documentation for libev" />	6	<meta name="description" content="Pod documentation for libev" />
7	<meta name="inputfile" content="<standard input>" />	7	<meta name="inputfile" content="<standard input>" />
8	<meta name="outputfile" content="<standard output>" />	8	<meta name="outputfile" content="<standard output>" />
9	<meta name="created" content="Mon Nov 26 11:20:35 2007" />	9	<meta name="created" content="Tue Nov 27 20:38:24 2007" />
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12	<body>	12	<body>
13	<div class="pod">	13	<div class="pod">
14	<!-- INDEX START -->	14	<!-- INDEX START -->
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31	<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a></li>	31	<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a></li>
32	<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li>	32	<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li>
33	<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li>	33	<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li>
34	<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li>	34	<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li>
35	<li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li>	35	<li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li>
		36	<li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a></li>
36	<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</a></li>	37	<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</a></li>
37	<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</a></li>	38	<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</a></li>
38	<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li>	39	<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li>
		40	<li><a href="#code_ev_fork_code_the_audacity_to_re"><code>ev_fork</code> - the audacity to resume the event loop after a fork</a></li>
39	</ul>	41	</ul>
40	</li>	42	</li>
41	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>	43	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
42	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>	44	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
43	<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>	45	<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>
		46	<li><a href="#MACRO_MAGIC">MACRO MAGIC</a></li>
44	<li><a href="#EMBEDDING">EMBEDDING</a>	47	<li><a href="#EMBEDDING">EMBEDDING</a>
45	<ul><li><a href="#FILESETS">FILESETS</a>	48	<ul><li><a href="#FILESETS">FILESETS</a>
46	<ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li>	49	<ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li>
47	<li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li>	50	<li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li>
48	<li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li>	51	<li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li>
…		…
113	the beginning of 1970, details are complicated, don't ask). This type is	116	the beginning of 1970, details are complicated, don't ask). This type is
114	called <code>ev_tstamp</code>, which is what you should use too. It usually aliases	117	called <code>ev_tstamp</code>, which is what you should use too. It usually aliases
115	to the <code>double</code> type in C, and when you need to do any calculations on	118	to the <code>double</code> type in C, and when you need to do any calculations on
116	it, you should treat it as such.</p>	119	it, you should treat it as such.</p>
117		120
118
119
120
121
122	</div>	121	</div>
123	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	122	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
124	<div id="GLOBAL_FUNCTIONS_CONTENT">	123	<div id="GLOBAL_FUNCTIONS_CONTENT">
125	<p>These functions can be called anytime, even before initialising the	124	<p>These functions can be called anytime, even before initialising the
126	library in any way.</p>	125	library in any way.</p>
…		…
180	might be supported on the current system, you would need to look at	179	might be supported on the current system, you would need to look at
181	<code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for	180	<code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for
182	recommended ones.</p>	181	recommended ones.</p>
183	<p>See the description of <code>ev_embed</code> watchers for more info.</p>	182	<p>See the description of <code>ev_embed</code> watchers for more info.</p>
184	</dd>	183	</dd>
185	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>	184	<dt>ev_set_allocator (void (cb)(void *ptr, size_t size))</dt>
186	<dd>	185	<dd>
187	<p>Sets the allocation function to use (the prototype is similar to the	186	<p>Sets the allocation function to use (the prototype and semantics are
188	realloc C function, the semantics are identical). It is used to allocate	187	identical to the realloc C function). It is used to allocate and free
189	and free memory (no surprises here). If it returns zero when memory	188	memory (no surprises here). If it returns zero when memory needs to be
190	needs to be allocated, the library might abort or take some potentially	189	allocated, the library might abort or take some potentially destructive
191	destructive action. The default is your system realloc function.</p>	190	action. The default is your system realloc function.</p>
192	<p>You could override this function in high-availability programs to, say,	191	<p>You could override this function in high-availability programs to, say,
193	free some memory if it cannot allocate memory, to use a special allocator,	192	free some memory if it cannot allocate memory, to use a special allocator,
194	or even to sleep a while and retry until some memory is available.</p>	193	or even to sleep a while and retry until some memory is available.</p>
195	<p>Example: replace the libev allocator with one that waits a bit and then	194	<p>Example: replace the libev allocator with one that waits a bit and then
196	retries: better than mine).</p>	195	retries: better than mine).</p>
197	<pre> static void *	196	<pre> static void *
198	persistent_realloc (void *ptr, long size)	197	persistent_realloc (void *ptr, size_t size)
199	{	198	{
200	for (;;)	199	for (;;)
201	{	200	{
202	void *newptr = realloc (ptr, size);	201	void *newptr = realloc (ptr, size);
203		202
…		…
586	</dd>	585	</dd>
587	<dt><code>EV_CHILD</code></dt>	586	<dt><code>EV_CHILD</code></dt>
588	<dd>	587	<dd>
589	<p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>	588	<p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>
590	</dd>	589	</dd>
		590	<dt><code>EV_STAT</code></dt>
		591	<dd>
		592	<p>The path specified in the <code>ev_stat</code> watcher changed its attributes somehow.</p>
		593	</dd>
591	<dt><code>EV_IDLE</code></dt>	594	<dt><code>EV_IDLE</code></dt>
592	<dd>	595	<dd>
593	<p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>	596	<p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>
594	</dd>	597	</dd>
595	<dt><code>EV_PREPARE</code></dt>	598	<dt><code>EV_PREPARE</code></dt>
…		…
600	<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any	603	<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any
601	received events. Callbacks of both watcher types can start and stop as	604	received events. Callbacks of both watcher types can start and stop as
602	many watchers as they want, and all of them will be taken into account	605	many watchers as they want, and all of them will be taken into account
603	(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep	606	(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep
604	<code>ev_loop</code> from blocking).</p>	607	<code>ev_loop</code> from blocking).</p>
		608	</dd>
		609	<dt><code>EV_EMBED</code></dt>
		610	<dd>
		611	<p>The embedded event loop specified in the <code>ev_embed</code> watcher needs attention.</p>
		612	</dd>
		613	<dt><code>EV_FORK</code></dt>
		614	<dd>
		615	<p>The event loop has been resumed in the child process after fork (see
		616	<code>ev_fork</code>).</p>
605	</dd>	617	</dd>
606	<dt><code>EV_ERROR</code></dt>	618	<dt><code>EV_ERROR</code></dt>
607	<dd>	619	<dd>
608	<p>An unspecified error has occured, the watcher has been stopped. This might	620	<p>An unspecified error has occured, the watcher has been stopped. This might
609	happen because the watcher could not be properly started because libev	621	happen because the watcher could not be properly started because libev
…		…
732		744
733	</div>	745	</div>
734	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>	746	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>
735	<div id="WATCHER_TYPES_CONTENT">	747	<div id="WATCHER_TYPES_CONTENT">
736	<p>This section describes each watcher in detail, but will not repeat	748	<p>This section describes each watcher in detail, but will not repeat
737	information given in the last section.</p>	749	information given in the last section. Any initialisation/set macros,
		750	functions and members specific to the watcher type are explained.</p>
		751	<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
		752	while the watcher is active, you can look at the member and expect some
		753	sensible content, but you must not modify it (you can modify it while the
		754	watcher is stopped to your hearts content), or <i>[read-write]</i>, which
		755	means you can expect it to have some sensible content while the watcher
		756	is active, but you can also modify it. Modifying it may not do something
		757	sensible or take immediate effect (or do anything at all), but libev will
		758	not crash or malfunction in any way.</p>
738		759
739		760
740		761
741		762
742		763
…		…
781	<dd>	802	<dd>
782	<p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to	803	<p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to
783	rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or	804	rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or
784	<code>EV_READ \| EV_WRITE</code> to receive the given events.</p>	805	<code>EV_READ \| EV_WRITE</code> to receive the given events.</p>
785	</dd>	806	</dd>
		807	<dt>int fd [read-only]</dt>
		808	<dd>
		809	<p>The file descriptor being watched.</p>
		810	</dd>
		811	<dt>int events [read-only]</dt>
		812	<dd>
		813	<p>The events being watched.</p>
		814	</dd>
786	</dl>	815	</dl>
787	<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well	816	<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
788	readable, but only once. Since it is likely line-buffered, you could	817	readable, but only once. Since it is likely line-buffered, you could
789	attempt to read a whole line in the callback:</p>	818	attempt to read a whole line in the callback:</p>
790	<pre> static void	819	<pre> static void
…		…
847	repeating. The exact semantics are:</p>	876	repeating. The exact semantics are:</p>
848	<p>If the timer is started but nonrepeating, stop it.</p>	877	<p>If the timer is started but nonrepeating, stop it.</p>
849	<p>If the timer is repeating, either start it if necessary (with the repeat	878	<p>If the timer is repeating, either start it if necessary (with the repeat
850	value), or reset the running timer to the repeat value.</p>	879	value), or reset the running timer to the repeat value.</p>
851	<p>This sounds a bit complicated, but here is a useful and typical	880	<p>This sounds a bit complicated, but here is a useful and typical
852	example: Imagine you have a tcp connection and you want a so-called idle	881	example: Imagine you have a tcp connection and you want a so-called
853	timeout, that is, you want to be called when there have been, say, 60	882	idle timeout, that is, you want to be called when there have been,
854	seconds of inactivity on the socket. The easiest way to do this is to	883	say, 60 seconds of inactivity on the socket. The easiest way to do
855	configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each	884	this is to configure an <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling
856	time you successfully read or write some data. If you go into an idle	885	<code>ev_timer_again</code> each time you successfully read or write some data. If
857	state where you do not expect data to travel on the socket, you can stop	886	you go into an idle state where you do not expect data to travel on the
858	the timer, and again will automatically restart it if need be.</p>	887	socket, you can stop the timer, and again will automatically restart it if
		888	need be.</p>
		889	<p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether
		890	and only ever use the <code>repeat</code> value:</p>
		891	<pre> ev_timer_init (timer, callback, 0., 5.);
		892	ev_timer_again (loop, timer);
		893	...
		894	timer->again = 17.;
		895	ev_timer_again (loop, timer);
		896	...
		897	timer->again = 10.;
		898	ev_timer_again (loop, timer);
		899
		900	</pre>
		901	<p>This is more efficient then stopping/starting the timer eahc time you want
		902	to modify its timeout value.</p>
		903	</dd>
		904	<dt>ev_tstamp repeat [read-write]</dt>
		905	<dd>
		906	<p>The current <code>repeat</code> value. Will be used each time the watcher times out
		907	or <code>ev_timer_again</code> is called and determines the next timeout (if any),
		908	which is also when any modifications are taken into account.</p>
859	</dd>	909	</dd>
860	</dl>	910	</dl>
861	<p>Example: create a timer that fires after 60 seconds.</p>	911	<p>Example: create a timer that fires after 60 seconds.</p>
862	<pre> static void	912	<pre> static void
863	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	913	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
…		…
981	<p>Simply stops and restarts the periodic watcher again. This is only useful	1031	<p>Simply stops and restarts the periodic watcher again. This is only useful
982	when you changed some parameters or the reschedule callback would return	1032	when you changed some parameters or the reschedule callback would return
983	a different time than the last time it was called (e.g. in a crond like	1033	a different time than the last time it was called (e.g. in a crond like
984	program when the crontabs have changed).</p>	1034	program when the crontabs have changed).</p>
985	</dd>	1035	</dd>
		1036	<dt>ev_tstamp interval [read-write]</dt>
		1037	<dd>
		1038	<p>The current interval value. Can be modified any time, but changes only
		1039	take effect when the periodic timer fires or <code>ev_periodic_again</code> is being
		1040	called.</p>
		1041	</dd>
		1042	<dt>ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]</dt>
		1043	<dd>
		1044	<p>The current reschedule callback, or <code>0</code>, if this functionality is
		1045	switched off. Can be changed any time, but changes only take effect when
		1046	the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
		1047	</dd>
986	</dl>	1048	</dl>
987	<p>Example: call a callback every hour, or, more precisely, whenever the	1049	<p>Example: call a callback every hour, or, more precisely, whenever the
988	system clock is divisible by 3600. The callback invocation times have	1050	system clock is divisible by 3600. The callback invocation times have
989	potentially a lot of jittering, but good long-term stability.</p>	1051	potentially a lot of jittering, but good long-term stability.</p>
990	<pre> static void	1052	<pre> static void
…		…
1039	<dt>ev_signal_set (ev_signal *, int signum)</dt>	1101	<dt>ev_signal_set (ev_signal *, int signum)</dt>
1040	<dd>	1102	<dd>
1041	<p>Configures the watcher to trigger on the given signal number (usually one	1103	<p>Configures the watcher to trigger on the given signal number (usually one
1042	of the <code>SIGxxx</code> constants).</p>	1104	of the <code>SIGxxx</code> constants).</p>
1043	</dd>	1105	</dd>
		1106	<dt>int signum [read-only]</dt>
		1107	<dd>
		1108	<p>The signal the watcher watches out for.</p>
		1109	</dd>
1044	</dl>	1110	</dl>
1045		1111
1046		1112
1047		1113
1048		1114
…		…
1061	at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see	1127	at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see
1062	the status word (use the macros from <code>sys/wait.h</code> and see your systems	1128	the status word (use the macros from <code>sys/wait.h</code> and see your systems
1063	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the	1129	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
1064	process causing the status change.</p>	1130	process causing the status change.</p>
1065	</dd>	1131	</dd>
		1132	<dt>int pid [read-only]</dt>
		1133	<dd>
		1134	<p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p>
		1135	</dd>
		1136	<dt>int rpid [read-write]</dt>
		1137	<dd>
		1138	<p>The process id that detected a status change.</p>
		1139	</dd>
		1140	<dt>int rstatus [read-write]</dt>
		1141	<dd>
		1142	<p>The process exit/trace status caused by <code>rpid</code> (see your systems
		1143	<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
		1144	</dd>
1066	</dl>	1145	</dl>
1067	<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p>	1146	<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p>
1068	<pre> static void	1147	<pre> static void
1069	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1148	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1070	{	1149	{
…		…
1072	}	1151	}
1073		1152
1074	struct ev_signal signal_watcher;	1153	struct ev_signal signal_watcher;
1075	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1154	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1076	ev_signal_start (loop, &sigint_cb);	1155	ev_signal_start (loop, &sigint_cb);
		1156
		1157
		1158
		1159
		1160	</pre>
		1161
		1162	</div>
		1163	<h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2>
		1164	<div id="code_ev_stat_code_did_the_file_attri-2">
		1165	<p>This watches a filesystem path for attribute changes. That is, it calls
		1166	<code>stat</code> regularly (or when the OS says it changed) and sees if it changed
		1167	compared to the last time, invoking the callback if it did.</p>
		1168	<p>The path does not need to exist: changing from "path exists" to "path does
		1169	not exist" is a status change like any other. The condition "path does
		1170	not exist" is signified by the <code>st_nlink</code> field being zero (which is
		1171	otherwise always forced to be at least one) and all the other fields of
		1172	the stat buffer having unspecified contents.</p>
		1173	<p>Since there is no standard to do this, the portable implementation simply
		1174	calls <code>stat (2)</code> regulalry on the path to see if it changed somehow. You
		1175	can specify a recommended polling interval for this case. If you specify
		1176	a polling interval of <code>0</code> (highly recommended!) then a <i>suitable,
		1177	unspecified default</i> value will be used (which you can expect to be around
		1178	five seconds, although this might change dynamically). Libev will also
		1179	impose a minimum interval which is currently around <code>0.1</code>, but thats
		1180	usually overkill.</p>
		1181	<p>This watcher type is not meant for massive numbers of stat watchers,
		1182	as even with OS-supported change notifications, this can be
		1183	resource-intensive.</p>
		1184	<p>At the time of this writing, no specific OS backends are implemented, but
		1185	if demand increases, at least a kqueue and inotify backend will be added.</p>
		1186	<dl>
		1187	<dt>ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)</dt>
		1188	<dt>ev_stat_set (ev_stat , const char path, ev_tstamp interval)</dt>
		1189	<dd>
		1190	<p>Configures the watcher to wait for status changes of the given
		1191	<code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to
		1192	be detected and should normally be specified as <code>0</code> to let libev choose
		1193	a suitable value. The memory pointed to by <code>path</code> must point to the same
		1194	path for as long as the watcher is active.</p>
		1195	<p>The callback will be receive <code>EV_STAT</code> when a change was detected,
		1196	relative to the attributes at the time the watcher was started (or the
		1197	last change was detected).</p>
		1198	</dd>
		1199	<dt>ev_stat_stat (ev_stat *)</dt>
		1200	<dd>
		1201	<p>Updates the stat buffer immediately with new values. If you change the
		1202	watched path in your callback, you could call this fucntion to avoid
		1203	detecting this change (while introducing a race condition). Can also be
		1204	useful simply to find out the new values.</p>
		1205	</dd>
		1206	<dt>ev_statdata attr [read-only]</dt>
		1207	<dd>
		1208	<p>The most-recently detected attributes of the file. Although the type is of
		1209	<code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types
		1210	suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there
		1211	was some error while <code>stat</code>ing the file.</p>
		1212	</dd>
		1213	<dt>ev_statdata prev [read-only]</dt>
		1214	<dd>
		1215	<p>The previous attributes of the file. The callback gets invoked whenever
		1216	<code>prev</code> != <code>attr</code>.</p>
		1217	</dd>
		1218	<dt>ev_tstamp interval [read-only]</dt>
		1219	<dd>
		1220	<p>The specified interval.</p>
		1221	</dd>
		1222	<dt>const char *path [read-only]</dt>
		1223	<dd>
		1224	<p>The filesystem path that is being watched.</p>
		1225	</dd>
		1226	</dl>
		1227	<p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p>
		1228	<pre> static void
		1229	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
		1230	{
		1231	/* /etc/passwd changed in some way */
		1232	if (w->attr.st_nlink)
		1233	{
		1234	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1235	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1236	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1237	}
		1238	else
		1239	/* you shalt not abuse printf for puts */
		1240	puts ("wow, /etc/passwd is not there, expect problems. "
		1241	"if this is windows, they already arrived\n");
		1242	}
		1243
		1244	...
		1245	ev_stat passwd;
		1246
		1247	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1248	ev_stat_start (loop, &passwd);
1077		1249
1078		1250
1079		1251
1080		1252
1081	</pre>	1253	</pre>
…		…
1303	<dt>ev_embed_sweep (loop, ev_embed *)</dt>	1475	<dt>ev_embed_sweep (loop, ev_embed *)</dt>
1304	<dd>	1476	<dd>
1305	<p>Make a single, non-blocking sweep over the embedded loop. This works	1477	<p>Make a single, non-blocking sweep over the embedded loop. This works
1306	similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most	1478	similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
1307	apropriate way for embedded loops.</p>	1479	apropriate way for embedded loops.</p>
		1480	</dd>
		1481	<dt>struct ev_loop *loop [read-only]</dt>
		1482	<dd>
		1483	<p>The embedded event loop.</p>
		1484	</dd>
		1485	</dl>
		1486
		1487
		1488
		1489
		1490
		1491	</div>
		1492	<h2 id="code_ev_fork_code_the_audacity_to_re"><code>ev_fork</code> - the audacity to resume the event loop after a fork</h2>
		1493	<div id="code_ev_fork_code_the_audacity_to_re-2">
		1494	<p>Fork watchers are called when a <code>fork ()</code> was detected (usually because
		1495	whoever is a good citizen cared to tell libev about it by calling
		1496	<code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the
		1497	event loop blocks next and before <code>ev_check</code> watchers are being called,
		1498	and only in the child after the fork. If whoever good citizen calling
		1499	<code>ev_default_fork</code> cheats and calls it in the wrong process, the fork
		1500	handlers will be invoked, too, of course.</p>
		1501	<dl>
		1502	<dt>ev_fork_init (ev_signal *, callback)</dt>
		1503	<dd>
		1504	<p>Initialises and configures the fork watcher - it has no parameters of any
		1505	kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless,
		1506	believe me.</p>
1308	</dd>	1507	</dd>
1309	</dl>	1508	</dl>
1310		1509
1311		1510
1312		1511
…		…
1462	</dd>	1661	</dd>
1463	<dt>w->sweep () <code>ev::embed</code> only</dt>	1662	<dt>w->sweep () <code>ev::embed</code> only</dt>
1464	<dd>	1663	<dd>
1465	<p>Invokes <code>ev_embed_sweep</code>.</p>	1664	<p>Invokes <code>ev_embed_sweep</code>.</p>
1466	</dd>	1665	</dd>
		1666	<dt>w->update () <code>ev::stat</code> only</dt>
		1667	<dd>
		1668	<p>Invokes <code>ev_stat_stat</code>.</p>
		1669	</dd>
1467	</dl>	1670	</dl>
1468	</p>	1671	</p>
1469	</dd>	1672	</dd>
1470	</dl>	1673	</dl>
1471	<p>Example: Define a class with an IO and idle watcher, start one of them in	1674	<p>Example: Define a class with an IO and idle watcher, start one of them in
…		…
1482	: io (this, &myclass::io_cb),	1685	: io (this, &myclass::io_cb),
1483	idle (this, &myclass::idle_cb)	1686	idle (this, &myclass::idle_cb)
1484	{	1687	{
1485	io.start (fd, ev::READ);	1688	io.start (fd, ev::READ);
1486	}	1689	}
		1690
		1691
		1692
		1693
		1694	</pre>
		1695
		1696	</div>
		1697	<h1 id="MACRO_MAGIC">MACRO MAGIC</h1><p><a href="#TOP" class="toplink">Top</a></p>
		1698	<div id="MACRO_MAGIC_CONTENT">
		1699	<p>Libev can be compiled with a variety of options, the most fundemantal is
		1700	<code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and
		1701	callbacks have an initial <code>struct ev_loop *</code> argument.</p>
		1702	<p>To make it easier to write programs that cope with either variant, the
		1703	following macros are defined:</p>
		1704	<dl>
		1705	<dt><code>EV_A</code>, <code>EV_A_</code></dt>
		1706	<dd>
		1707	<p>This provides the loop <i>argument</i> for functions, if one is required ("ev
		1708	loop argument"). The <code>EV_A</code> form is used when this is the sole argument,
		1709	<code>EV_A_</code> is used when other arguments are following. Example:</p>
		1710	<pre> ev_unref (EV_A);
		1711	ev_timer_add (EV_A_ watcher);
		1712	ev_loop (EV_A_ 0);
		1713
		1714	</pre>
		1715	<p>It assumes the variable <code>loop</code> of type <code>struct ev_loop *</code> is in scope,
		1716	which is often provided by the following macro.</p>
		1717	</dd>
		1718	<dt><code>EV_P</code>, <code>EV_P_</code></dt>
		1719	<dd>
		1720	<p>This provides the loop <i>parameter</i> for functions, if one is required ("ev
		1721	loop parameter"). The <code>EV_P</code> form is used when this is the sole parameter,
		1722	<code>EV_P_</code> is used when other parameters are following. Example:</p>
		1723	<pre> // this is how ev_unref is being declared
		1724	static void ev_unref (EV_P);
		1725
		1726	// this is how you can declare your typical callback
		1727	static void cb (EV_P_ ev_timer *w, int revents)
		1728
		1729	</pre>
		1730	<p>It declares a parameter <code>loop</code> of type <code>struct ev_loop *</code>, quite
		1731	suitable for use with <code>EV_A</code>.</p>
		1732	</dd>
		1733	<dt><code>EV_DEFAULT</code>, <code>EV_DEFAULT_</code></dt>
		1734	<dd>
		1735	<p>Similar to the other two macros, this gives you the value of the default
		1736	loop, if multiple loops are supported ("ev loop default").</p>
		1737	</dd>
		1738	</dl>
		1739	<p>Example: Declare and initialise a check watcher, working regardless of
		1740	wether multiple loops are supported or not.</p>
		1741	<pre> static void
		1742	check_cb (EV_P_ ev_timer *w, int revents)
		1743	{
		1744	ev_check_stop (EV_A_ w);
		1745	}
		1746
		1747	ev_check check;
		1748	ev_check_init (&check, check_cb);
		1749	ev_check_start (EV_DEFAULT_ &check);
		1750	ev_loop (EV_DEFAULT_ 0);
		1751
		1752
		1753
1487		1754
1488	</pre>	1755	</pre>
1489		1756
1490	</div>	1757	</div>
1491	<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p>	1758	<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p>
…		…
1702	will have the <code>struct ev_loop *</code> as first argument, and you can create	1969	will have the <code>struct ev_loop *</code> as first argument, and you can create
1703	additional independent event loops. Otherwise there will be no support	1970	additional independent event loops. Otherwise there will be no support
1704	for multiple event loops and there is no first event loop pointer	1971	for multiple event loops and there is no first event loop pointer
1705	argument. Instead, all functions act on the single default loop.</p>	1972	argument. Instead, all functions act on the single default loop.</p>
1706	</dd>	1973	</dd>
1707	<dt>EV_PERIODICS</dt>	1974	<dt>EV_PERIODIC_ENABLE</dt>
1708	<dd>	1975	<dd>
1709	<p>If undefined or defined to be <code>1</code>, then periodic timers are supported,	1976	<p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If
1710	otherwise not. This saves a few kb of code.</p>	1977	defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
		1978	code.</p>
		1979	</dd>
		1980	<dt>EV_EMBED_ENABLE</dt>
		1981	<dd>
		1982	<p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If
		1983	defined to be <code>0</code>, then they are not.</p>
		1984	</dd>
		1985	<dt>EV_STAT_ENABLE</dt>
		1986	<dd>
		1987	<p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If
		1988	defined to be <code>0</code>, then they are not.</p>
		1989	</dd>
		1990	<dt>EV_FORK_ENABLE</dt>
		1991	<dd>
		1992	<p>If undefined or defined to be <code>1</code>, then fork watchers are supported. If
		1993	defined to be <code>0</code>, then they are not.</p>
		1994	</dd>
		1995	<dt>EV_MINIMAL</dt>
		1996	<dd>
		1997	<p>If you need to shave off some kilobytes of code at the expense of some
		1998	speed, define this symbol to <code>1</code>. Currently only used for gcc to override
		1999	some inlining decisions, saves roughly 30% codesize of amd64.</p>
		2000	</dd>
		2001	<dt>EV_PID_HASHSIZE</dt>
		2002	<dd>
		2003	<p><code>ev_child</code> watchers use a small hash table to distribute workload by
		2004	pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more
		2005	than enough. If you need to manage thousands of children you might want to
		2006	increase this value.</p>
1711	</dd>	2007	</dd>
1712	<dt>EV_COMMON</dt>	2008	<dt>EV_COMMON</dt>
1713	<dd>	2009	<dd>
1714	<p>By default, all watchers have a <code>void *data</code> member. By redefining	2010	<p>By default, all watchers have a <code>void *data</code> member. By redefining
1715	this macro to a something else you can include more and other types of	2011	this macro to a something else you can include more and other types of

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Revision 1.52 by root, Tue Nov 27 19:41:52 2007 UTC